Perforin 1 (PRF1) is a cytolytic protein found in the granules of Cytotoxic T lymphocytes (CTLs) and NK cells. Upon degranulation, perforin inserts itself into the target cell's plasma membrane, forming a pore. The lytic membrane-inserting part of perforin is the MACPF domain. This region shares homology with cholesterol-dependent cytolysins from Gram-positive bacteria. It has been demonstrated that PRF1 causes the lysis of abnormal body cells and the elimination of virus-infected cells and tumors.To test the effect of PRF1 on cell apoptosis，Hela cells were seeded into triplicate wells of 96-well plates and allowed to attach, replaced with various concentrations of recombinant human PRF1. After incubated for 72h, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10 μl of CCK-8 solution was added to each well of the plate, then the absorbance at 450 nm was measured using a microplate reader after incubating the plate for 1-4 hours at 37 ℃. Cell viability was assessed by CCK-8 assay after incubation with recombinant human PRF1 for 72h. The result was shown in Figure 1. It was obvious that PRF1 significantly decreased cell viability of Hela cells. The ED50 of recombinant human PRF1 is 1.985 μg/ml.